ram: rk3399: migrate to use common code

For there are some structures and functions are common for all rockchip SoCs,
migrate to use the common code so that we can clean up reduandent codes.

Signed-off-by: YouMin Chen <cym@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/drivers/ram/rockchip/Makefile b/drivers/ram/rockchip/Makefile
index b477f70..217366b 100644
--- a/drivers/ram/rockchip/Makefile
+++ b/drivers/ram/rockchip/Makefile
@@ -10,5 +10,5 @@
 obj-$(CONFIG_ROCKCHIP_RK322X) = sdram_rk322x.o
 obj-$(CONFIG_ROCKCHIP_RK3288) = sdram_rk3288.o
 obj-$(CONFIG_ROCKCHIP_RK3328) = sdram_rk3328.o sdram_pctl_px30.o sdram_phy_px30.o
-obj-$(CONFIG_RAM_RK3399) += sdram_rk3399.o
+obj-$(CONFIG_ROCKCHIP_RK3399) += sdram_rk3399.o
 obj-$(CONFIG_ROCKCHIP_SDRAM_COMMON) += sdram_common.o